Boring bar



Jan. 10, 1961 M- FORSYTH ETAL 2,967,442

BORING BAR Original Filed ma 28, 1957 INVENTOR MAME? M F0195) 7/7 BY 46fATTO R N EY5 United States Patent BORING BAR James M. Forsyth and JackG. Clark, Houston, Tex., assignors to Forsyth Engineering Company,Houston, Tex., a corporation of Texas Continuation of application Ser.No. 662,195, May 28, This application Feb. 2, 1960, Ser. No.

1 Claim. (Cl. 77-58) Our invention relates to a tool holder and will bedescribed in relation to and as embodied in a boring bar. The principlesof the invention are of broader application and the term boring bar isused in a broader sense to indicate any tool holder, such as a boringbar, or a lathe tool holder or the like. Furthermore, vthe term carbidetool is intended to cover a ceramic .or other mechanically held inserttool.

This is a continuation of patent application Serial No. 662,195, filedMay 28, 1957, now abandoned.

It is an object of the invention to provide a boring bar which is sturdyin construction and provides adequate support beneath the tool at thefront end.

It is another object to provide an improved boring bar for carbide toolswith improved means for holding the tool in place.

Still another object is to provide a boring bar wherein there aresubstantially no projections or recesses adjacent the cutting edge whichmight collect chips.

A further object is to provide an improved boring bar having improvedmeans for transmitting cutting force on the carbide tool to the mainbody of the bar so as to provide great security and avoid chatter.

Another object is to provide a boring bar having improved means for verysecurely holding a carbide tool in place on the bar.

Another object is to provide a boring bar with improved means forconducting coolant to the zone adjacent the cutting edge.

Further an object is to provide a boring bar having improved chipbreaker means which at the same time assists in holding a carbide toolin place.

Other objects and various features of novelty and invention will behereinafter pointed out or will become apparent to those skilled in theart.

Briefly stated, in a preferred form of the invention, we provide a toolholder bar and the forward end is preferably bent at a lateral angle tothe bar so that the tool projecting at the front may have sufficientprojection without any danger of interference between the bar at therear and the work piece. Better tool support is also thus obtained. Theforward end of the boring bar has a transverse opening in the topthereof extending part way through the bar and forming a bottom seat anda rear seat. The opening extends all the way to the front and preferablyhas parallel sides. Within the opening is a clamp nut for holding thecarbide tool in place in the opening and this clamp nut at the top ispreferably substantially flush with the rest of the bar adjacent theedges of the opening and this nut preferably engages the rear seat atthe rear of the transverse opening. The side walls of the opening arepreferably parallel so as to fit the parallel sides of the clamping nut.The carbide tool is placed in the opening and the nut holds the same inplace and there may also be a chip breaker to assist in holding thecarbide tool in place and there may also be an anvil member resting onthe bottom of the transverse opening. Preferably, there are noprojections at the top or any openings to catch chips.

The clamp screw. preferably extends up through the bar and into theclamp nut for drawing the same downwardly for holding the carbide toolin place.

1 In the drawings, which show for illustrative .purposes only, apreferred form of the invention:

Fig. 1 is a top plan view of a boring bar illustrating features of theinvention;

Fig. 2 is a sectional view, taken substantially in the plane of the line2-2 of Fig. 1;

Fig. 3 is a sectional view, taken substantially in the plane of the line3-3 of Fig. 2.

In said drawings, the tool holder herein referred to and called a boringbar 5 has an extended shank for securement to a suitable slide, turret'or the like. The forward end of the bar retaining the same diameter isbent .at an angle, as indicated at 6, and 'it is on this angularly bentbar that the tool is carried so that the tool may project sidewise, asit does as shown particularly in Fig. 1. There is then no danger of anycollision between the main shank and the work piece as the boring bar isfed in.

The forward end of the bar is preferably provided with a transverseopening 7 extending upward through the bar and providing a rear seatsurface 8 and a bottom seat surface 9. The opening is open at the topand open at the front and the top of the bar is s'lab'bed off, asindicated particularly in Fig. 3, and preferably at the side, asindicated at 10. In the preferred form there is an anvil member 11 whichmay be of carbide and rests on the bottom seat 9 and a carbide tool orbit 12 rests on the bottom seat, namely in this case on the anvil 11. Inthe preferred form there is a chip breaker 13 resting on the tool and aclamp nut 14 has a forward end 15 which rests about centrally of thetool 12, but in this case on the chip breaker 13, which in turn rests onthe tool 12 and forces the latter down on to its seat. The clamp nutextends downwardly into the opening 7 and there is a heel 16 at thebottom resting on the bottom surface either of the opening or on theanvil 11. The remainder of the nut 14 is preferably free of the anvil,as shown especially in Fig. 3, and preferably has clearance with thechip breaker 13, as shown, so that only the tip 15 engages the chipbreaker. The clamp screw 17 extends up through the bottom of the bar 6and into the clamp nut 14 for drawing the latter downwardly. Thisdownward drawing by the clamp screw 17 tends to cause the clamp nut topivot about the heel 16 so as to cause the forward end 15 to press withgreat force on the chip breaker and the tool. It will be seen then thatby having clearance between the clamp nut 14 and the chip breaker aswell as between it and the anvil member 11, there is no danger of havingthe nut bottom without holding the tool 12 securely in place.

In the form illustrated the carbide tool 12 is square and is of thevariety that is turned until all of its edges have been used up and isthen discarded. In order to protect the cutting edges of the tool 12,the sides of the slot 7 may be relieved, as indicated at 18-48 so thatthe cutting edges of the tool will not engage the sides of the openingwhen the tool is put in place or held therein. The tool at the rear alsoengages the rear or intermediate portion of the clamp nut 14 and it willbe seen that the clamp nut at such intermediate surface is relieved, asindicated at 19 for protecting the rear edge of the tool 12.

Any rearward cutting force on the tool 12 will be transmitted directlyto the intermediate surface of the clamp nut 14 at the relieved portionand through the nut 14 itself, such force will be transmitted directlyto the sturdy boring bar itself. The downward cutting force on the toolwill be transmitted through the anvil, when one is provided, directly tothe bottom seat portion of the sturdy boring bar which, due to theangular turn of the forward end, provides considerable metal uncle: thebottom of the tool for sustaining any cutting load.

The boring bar is preferably drilled, as indicated at 20, fortransmitting coolant through the bar and to the forward end thereof. Atthe forward end the opening 20 opens into the transverse opening 7 inthe bar and connects with the coolant passage 21 in the clamp nut 14.Thus, coolant supplied to the boring bar will be flushed out to thecutting zone so as to keep the tool cool and wash away chips. Thecoolant thus flowed out into the cutting zone will not be carried awayby the rotating work.

We have described the boring bar in a complete preferred form whereinthere is a separate anvil member '11 seated on the bottom surface 9 inthe transverse opening 7 in the bar and we have also described a specialchip breaker 13 which rests on the top of the carbide tool 12 and isitself engaged by the forward end 15 of the clamp nut 14. It will beunderstood, however, that it is not at all times necessary to have achip breaker, in which case the chip breaker would be omitted and theclamp nut would fit directly on the tool 12. Furthermore, if the seat 9in the bottom of the transverse opening is a good seat, it may notalways be necessary to have the separate anvil member 11 and in thatcase the anvil may be omitted, or in other words the opening 7 need notbe made quite so deep, and what is now the seat surface of the anvil maybe the bottom surface of the opening. Therefore, in some of the claimswe have referred to the carbide tool as being supported by the bottom ofthe opening and have also referred to the forward end of the clamp nutas engaging the middle of the tool 12 to hold it in place. These claimsare simply designed to cover those cases where a chip breaker is notneeded and where an anvil 11 would not be needed. Even without the chipbreaker and without the anvil many of the improved features of theinvention would still be present.

There are no top projections to catch chips and there are no recessesfor catching or receiving chips. It will be seen that the tool will bewell protected when in place on the holder and therefore all of itsedges may be used and then the tool is discarded. It will also be seenthat the tool is adequately backed up rearwardly by the clamp nut andthrough it by the boring bar itself. The tool is acked up at the bottomby an anvil when one is empioyed and by the heavy metal of the barbeneath the tool. Due to the clearances and the tilting action of thenut 14 there is ractically no tendency for the nut to ever seat and thetool will always be securely held in place.

While the invention has been described in considerable detail, and apreferred form illustrated, it is to be understood that variousIIlOdlfiCatlCIlS and changes may be made within the scope of theinvention, as defined in the appended claim.

We claim:

In a boring bar, a bar having the top fron. part slabbed off, said barat the front end having a notch extending from the front rearwardly andopening at the top in said slabbed 01f portion, an anvil extending fromthe front of said notch to abutting relation therewith at the rear, saidanvil lying flat on the bottom of the notch, a carbide tool resting ontop of said anvil and confined at the sides by the lateral sides of saidnotch, a chip breaker resting on said tool, a clamp nut fitted entirelywithin said notch, said clamp nut having its forward edge only restingon said chip breaker and having its rear edge in said notch and restingon top of said anvil so as to pivot thereon when drawn down and causethe front end of said nut to tightly clasp said chip breaker and tooland anvil in said notch, the top of said clamp nut being slabbed off atthe top so as to form a continuation of the slabbed oif end of said bar,a substantially vertical surface on said clamp nut beneath and recessedfrom its forward end and having a transverse groove therein intermediateits extremities to receive the upper rearward edge of said carbide tool,the lower portion of said vertical surface below said transverse grooveforming an abutment surface for said carbide tool, and a screw extendingup through said bar and into said clamp nut to draw the latterdownwardly in clamping direction.

No references cited.

